Is this a problem? On 10.10 there aren't packages depending on libirrlicht1.7 and on natty 1.7.2 is highly recommended due to 1.7.1 bugs with supertuxkart 0.7 (crash, graphic corruption, keyboard not working on full screen).

It might at least break anything locally build using the 1.7.1 package. The breakage itself is in theory easy-ish to fix -- just patch the handfull of *virtual* destructors back in -- it's just not really rewarding and I have a lot of other stuff to do. Might appear soon or not at all depending.

Don't think making a exception now and let the broken ABI slip in is wise in long term.